diff --git a/CMakeLists.txt b/CMakeLists.txt
index e04676a..5ba45c9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.24 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.18...3.24 FATAL_ERROR)
 
 # cmake setup begin
 project(green_crdt)
diff --git a/version3/CMakeLists.txt b/version3/CMakeLists.txt
index 79d0223..0ade307 100644
--- a/version3/CMakeLists.txt
+++ b/version3/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.9...3.24 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.18...3.24 FATAL_ERROR)
 
 project(crdt_version3 CXX C)